GHSA-JR6P-8PJJ-MFX6
Vulnerability from github – Published: 2026-07-31 16:53 – Updated: 2026-07-31 16:53Summary
CVE-2026-22872 (GHSA-qjjm-7j9w-pw72) reported that a Tenant Owner could create cluster-scoped resources
(e.g. ClusterRole, ValidatingWebhookConfiguration) through a TenantResource, because the controller
applies them with its cluster-admin ServiceAccount and SetNamespace is ineffective for cluster-scoped
kinds. The v0.13.0 fix added a cluster-scope rejection guard, but only on the NamespacedItems selection
path (ResourceReference.LoadResources -> IsNamespacedGVK, error "cluster-scoped kind ... is not
allowed"). The RawItems create path — the exact vector the original advisory named — and the Generators
path were not given this guard. The vulnerability therefore persists in all releases v0.13.0 through
v0.13.7 and on trunk HEAD (8d89d6865d).
Details
TenantResource reconcile flow:
- internal/controllers/resources/namespaced.go reconcile() obtains the apply client via loadClient();
by default (impersonation off, no Spec.ServiceAccount) this is the manager client whose SA is bound to
cluster-admin (charts/capsule/templates/rbac.yaml:488-501, {fullname}-manager-rolebinding ->
roleRef cluster-admin).
- Collector.Collect() (collect.go) processes spec.RawItems via handleRawItem and spec.Generators
via handleGeneratorItem.
handleRawItem (collect.go:406-425, trunk HEAD — byte-identical to v0.13.0):
tmplString := tpl.FastTemplate(string(item.Raw), opts.Iterator.FastContext)
obj := &unstructured.Unstructured{}
unstructured.UnstructuredJSONScheme.Decode([]byte(tmplString), nil, obj)
if ns != nil { obj.SetNamespace(ns.Name) } // ONLY mitigation
return obj, nil // NO IsNamespacedGVK / allowClusterScoped guard
handleGeneratorItem (collect.go:382-404) is the same: it only SetNamespaces on rendered objects.
The accumulated objects flow to pkg/api/processor/processor_func.go Reconcile() -> Apply() ->
clt.PatchApply(ctx, c, obj, ...) (line 167/378) with no scope check at any point.
By contrast, CollectNamespacedItems (collect.go:308) calls item.LoadResources(..., allowClusterScoped=false),
and pkg/template/reference.go:105-107 enforces:
if !allowClusterScoped && !isNamespaced {
return nil, fmt.Errorf("cluster-scoped kind %s/%s is not allowed", ...)
}
So the guard the fix added is real, but it sits on a different (selection) path than the one the CVE
described (RawItems create path). For cluster-scoped kinds, SetNamespace is ignored by the Kubernetes API
server, so the object is created cluster-wide by the cluster-admin client.
Parent-fix diff confirmation: in v0.12.4 the RawItems handler in processor.go was the vulnerable code
(obj.SetNamespace(ns.Name) then createOrUpdate via r.client). v0.13.0 refactored this into
collect.go handleRawItem but left it without the new guard.
Proof of Concept
A self-contained in-process Go test (incompletefix_poc_test.go), run against trunk HEAD with go1.26.4,
proves the asymmetry:
- TestRawItemPath_NoClusterScopeGuard: feeds a ClusterRole rawItem to handleRawItem -> object returned
unchanged, no rejection (PASS).
- TestNamespacedItemsPath_HasClusterScopeGuard: feeds the same ClusterRole kind to
LoadResources(allowClusterScoped=false) -> rejected with
"cluster-scoped kind rbac.authorization.k8s.io/v1/ClusterRole is not allowed" (PASS).
VULNERABLE: RawItems path accepted cluster-scoped rbac.authorization.k8s.io/v1/ClusterRole;
metadata.namespace="tenant-ns" (ignored by API server for cluster-scoped kinds)
GUARDED: NamespacedItems path correctly rejected cluster-scoped kind:
cluster-scoped kind rbac.authorization.k8s.io/v1/ClusterRole is not allowed
End-to-end (cluster) reproduction:
1. Deploy capsule (default Helm) with rbac.resources.create=true (the opt-in that exposes TenantResources
to tenant owners; the configuration the original CVE applies to).
2. As a Tenant Owner, create in a tenant namespace:
yaml
apiVersion: capsule.clastix.io/v1beta2
kind: TenantResource
metadata: {name: pwn, namespace: <tenant-ns>}
spec:
resources:
- namespaceSelector: {matchLabels: {capsule.clastix.io/tenant: <tenant>}}
rawItems:
- apiVersion: rbac.authorization.k8s.io/v1
kind: ClusterRole
metadata: {name: tenant-escalation}
rules: [{apiGroups: ["*"], resources: ["*"], verbs: ["*"]}]
3. Observe the cluster-scoped ClusterRole tenant-escalation is created by the cluster-admin controller,
despite the tenant owner lacking cluster RBAC to create it. Swap in ValidatingWebhookConfiguration
to intercept/exfiltrate cluster-wide Secrets.
Impact
A Tenant Owner (namespace-scoped) escalates to cluster-admin-equivalent privileges and can compromise all tenants and the cluster control plane. Identical impact to CVE-2026-22872; the v0.13.0 remediation does not close the RawItems/Generators vector.
Remediation
Apply the same IsNamespacedGVK / allowClusterScoped rejection inside handleRawItem and
handleGeneratorItem — or centrally in Collector.AddToAccumulation / processor.Apply — so the create
path enforces the same cluster-scope policy as the selection path. (GlobalTenantResource shares the path
but is not a privesc — cluster-admin-only to create.)
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 0.13.7"
},
"package": {
"ecosystem": "Go",
"name": "github.com/projectcapsule/capsule"
},
"ranges": [
{
"events": [
{
"introduced": "0.13.0"
},
{
"fixed": "0.13.8"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-65835"
],
"database_specific": {
"cwe_ids": [
"CWE-269",
"CWE-863"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-31T16:53:42Z",
"nvd_published_at": "2026-07-30T20:18:13Z",
"severity": "MODERATE"
},
"details": "### Summary\nCVE-2026-22872 (GHSA-qjjm-7j9w-pw72) reported that a Tenant Owner could create cluster-scoped resources\n(e.g. `ClusterRole`, `ValidatingWebhookConfiguration`) through a `TenantResource`, because the controller\napplies them with its cluster-admin ServiceAccount and `SetNamespace` is ineffective for cluster-scoped\nkinds. The v0.13.0 fix added a cluster-scope rejection guard, but **only on the NamespacedItems selection\npath** (`ResourceReference.LoadResources` -\u003e `IsNamespacedGVK`, error `\"cluster-scoped kind ... is not\nallowed\"`). The **RawItems create path \u2014 the exact vector the original advisory named \u2014 and the Generators\npath were not given this guard.** The vulnerability therefore persists in all releases **v0.13.0 through\nv0.13.7** and on trunk HEAD (`8d89d6865d`).\n\n### Details\nTenantResource reconcile flow:\n- `internal/controllers/resources/namespaced.go` `reconcile()` obtains the apply client via `loadClient()`;\n by default (impersonation off, no `Spec.ServiceAccount`) this is the manager client whose SA is bound to\n cluster-admin (`charts/capsule/templates/rbac.yaml:488-501`, `{fullname}-manager-rolebinding` -\u003e\n roleRef cluster-admin).\n- `Collector.Collect()` (`collect.go`) processes `spec.RawItems` via `handleRawItem` and `spec.Generators`\n via `handleGeneratorItem`.\n\n`handleRawItem` (`collect.go:406-425`, trunk HEAD \u2014 byte-identical to v0.13.0):\n```go\ntmplString := tpl.FastTemplate(string(item.Raw), opts.Iterator.FastContext)\nobj := \u0026unstructured.Unstructured{}\nunstructured.UnstructuredJSONScheme.Decode([]byte(tmplString), nil, obj)\nif ns != nil { obj.SetNamespace(ns.Name) } // ONLY mitigation\nreturn obj, nil // NO IsNamespacedGVK / allowClusterScoped guard\n```\n`handleGeneratorItem` (`collect.go:382-404`) is the same: it only `SetNamespace`s on rendered objects.\n\nThe accumulated objects flow to `pkg/api/processor/processor_func.go` `Reconcile()` -\u003e `Apply()` -\u003e\n`clt.PatchApply(ctx, c, obj, ...)` (line 167/378) with **no scope check at any point**.\n\nBy contrast, `CollectNamespacedItems` (`collect.go:308`) calls `item.LoadResources(..., allowClusterScoped=false)`,\nand `pkg/template/reference.go:105-107` enforces:\n```go\nif !allowClusterScoped \u0026\u0026 !isNamespaced {\n return nil, fmt.Errorf(\"cluster-scoped kind %s/%s is not allowed\", ...)\n}\n```\nSo the guard the fix added is real, but it sits on a different (selection) path than the one the CVE\ndescribed (RawItems create path). For cluster-scoped kinds, `SetNamespace` is ignored by the Kubernetes API\nserver, so the object is created cluster-wide by the cluster-admin client.\n\n**Parent-fix diff confirmation:** in v0.12.4 the RawItems handler in `processor.go` was the vulnerable code\n(`obj.SetNamespace(ns.Name)` then `createOrUpdate` via `r.client`). v0.13.0 refactored this into\n`collect.go` `handleRawItem` but left it without the new guard.\n\n### Proof of Concept\nA self-contained in-process Go test (`incompletefix_poc_test.go`), run against trunk HEAD with go1.26.4,\nproves the asymmetry:\n- `TestRawItemPath_NoClusterScopeGuard`: feeds a `ClusterRole` rawItem to `handleRawItem` -\u003e object returned\n unchanged, no rejection (PASS).\n- `TestNamespacedItemsPath_HasClusterScopeGuard`: feeds the same `ClusterRole` kind to\n `LoadResources(allowClusterScoped=false)` -\u003e rejected with\n `\"cluster-scoped kind rbac.authorization.k8s.io/v1/ClusterRole is not allowed\"` (PASS).\n\n```\nVULNERABLE: RawItems path accepted cluster-scoped rbac.authorization.k8s.io/v1/ClusterRole;\n metadata.namespace=\"tenant-ns\" (ignored by API server for cluster-scoped kinds)\nGUARDED: NamespacedItems path correctly rejected cluster-scoped kind:\n cluster-scoped kind rbac.authorization.k8s.io/v1/ClusterRole is not allowed\n```\n\nEnd-to-end (cluster) reproduction:\n1. Deploy capsule (default Helm) with `rbac.resources.create=true` (the opt-in that exposes TenantResources\n to tenant owners; the configuration the original CVE applies to).\n2. As a Tenant Owner, create in a tenant namespace:\n ```yaml\n apiVersion: capsule.clastix.io/v1beta2\n kind: TenantResource\n metadata: {name: pwn, namespace: \u003ctenant-ns\u003e}\n spec:\n resources:\n - namespaceSelector: {matchLabels: {capsule.clastix.io/tenant: \u003ctenant\u003e}}\n rawItems:\n - apiVersion: rbac.authorization.k8s.io/v1\n kind: ClusterRole\n metadata: {name: tenant-escalation}\n rules: [{apiGroups: [\"*\"], resources: [\"*\"], verbs: [\"*\"]}]\n ```\n3. Observe the cluster-scoped ClusterRole `tenant-escalation` is created by the cluster-admin controller,\n despite the tenant owner lacking cluster RBAC to create it. Swap in `ValidatingWebhookConfiguration`\n to intercept/exfiltrate cluster-wide Secrets.\n\n### Impact\nA Tenant Owner (namespace-scoped) escalates to cluster-admin-equivalent privileges and can compromise all\ntenants and the cluster control plane. Identical impact to CVE-2026-22872; the v0.13.0 remediation does not\nclose the RawItems/Generators vector.\n\n### Remediation\nApply the same `IsNamespacedGVK` / `allowClusterScoped` rejection inside `handleRawItem` and\n`handleGeneratorItem` \u2014 or centrally in `Collector.AddToAccumulation` / `processor.Apply` \u2014 so the create\npath enforces the same cluster-scope policy as the selection path. (`GlobalTenantResource` shares the path\nbut is not a privesc \u2014 cluster-admin-only to create.)",
"id": "GHSA-jr6p-8pjj-mfx6",
"modified": "2026-07-31T16:53:42Z",
"published": "2026-07-31T16:53:42Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/projectcapsule/capsule/security/advisories/GHSA-jr6p-8pjj-mfx6"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-65835"
},
{
"type": "PACKAGE",
"url": "https://github.com/projectcapsule/capsule"
},
{
"type": "WEB",
"url": "https://github.com/projectcapsule/capsule/releases/tag/v0.13.8"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L",
"type": "CVSS_V3"
}
],
"summary": "Capsule has an incomplete fix of CVE-2026-22872: TenantResource RawItems and Generators still allow cluster-scoped resource creation (cross-tenant privilege escalation)"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.